In recent years, advances in wave technology and detecting devices associated therewith have allowed physicians to examine organs and other internal body features of patients without resort to invasive procedures which unavoidably involve the risk of infection and trauma attendant to all surgery, even that of the simple diagnostic variety. By use of such technology, including magnetic resonance, positron emission, ultra-sound, and similar techniques, in conjunction with wave detectors and data processing equipment, cross sections of the entire body are now readily obtainable. The advantages of the new diagnostic tools are so pronounced that most of the larger hospitals and similar facilities now have this equipment available for their staffs. Computerized axial tomography, for example, commonly known as CAT scan, once relatively exotic has now become common place, and such equipment is available for use throughout the country. Among the advantages of total body scanning may be mentioned the fact that the injection of radioisotopes is not required to produce a record of findings; it being possible to obtain images of tissue density across a complete cross section of the body being scanned without resort to such materials. The technique is particularly useful in visualizing the retroperitoneal space, for example, the pancreas, liver, spleen, and ovaries, as well as the abdominal section of the aeorta.
While such equipment has allowed physicians to view internal portions of the body previously inaccessible in the absence of surgery, one of the disadvantages of the equipment is the tendancy to over-expose patients to excessive amounts of wave energy during the scanning procedure. For example, in employing in such techniques, it is frequently necessary to provide a reference point relative to which internal features of the patient may be located, fluroscopically or on film, for subsequent biopsy, or for other purposes. Commonly such a reference point is established by placing a small piece of metal as a marker on the area of interest prior to exposing the patient to, for example, X-ray radiation. Quite often, however, after such placement and subsequent X-ray exposure, it is necessary to reposition the marker to make it more useful as a reference point. Such repositioning necessitates additional X-ray exposure, with still further adjustment and more X-ray exposures sometimes being found necessary. While small amounts of exposure to radiation are normally justified on a risk/benefit basis, X-ray exposures are cumulative and capable of producing adverse cellular changes, including malignancies, in tissue with which it comes in contact. Consequently, it is highly desirable to reduce exposure to such waves to the absolute minimum necessary to achieve the result desired.